1. Field of the Invention
The present invention relates to a two-terminal microelectronic device, and, in particular, to a two-terminal non-volatile resistor device, having a structure of electrode/perovskite-active-material-layer/electrode, which is an Electric-Pulse-Induced-Resistance change device, commonly referred to by the acronym EPIR.
2. Description of the Related Art
The properties of materials having a perovskite structure, among them colossal magneto-resistance (CMR) materials and high transition temperature superconductivity (HTSC) materials, can be changed significantly by external influences, such as temperature, magnetic field, electric field, photons, and pressure.
Traditional CMR resistance change effect under high magnetic fields, is set out, for example, in the paper “Growth, Transport, and Magnetic Properties of Pr0.67Ca0.33MnO3 Thin Films”, S. K. Singh, et al, Appl. Phys. Lett., vol. 69, pp. 263-265, 1996. The pulsed electric field or pulsed current through the sample cannot create a high enough magnetic induction to change the resistance of the PCMO.
The electric resistance of the perovskite materials, particularly CMR and HTSC materials, can be modified by applying one or more short electrical pulses to a thin film or bulk material. The electric field strength or electric current density of the pulse is sufficient to switch the physical state of the materials so as to modify the properties of the material. The pulse is desired to have low energy so as not to destroy the material. (S. Q. Liu, N. J. Wu, and A. Ignatiev, Applied Physics Letters, 76, 2749 (2000).) Multiple pulses may be applied to the material to produce incremental changes in properties of the material (S. Q. Liu, N. J. Wu, and A. Ignatiev, as disclosed in U.S. Pat. Nos. 6,204,139, and 6,473,332, which are incorporated herein by this reference). One of the properties that can be changed is the resistance of the material. The change may be partially or totally reversible using pulses of opposite polarities. This has been defined as the electrical pulse induced non-volatile resistance change effect, abbreviated as the EPIR effect. Based on the EPIR effect, a two terminal non-volatile resistor device, having a structure of electrode/perovskite-active-material-layer/electrode, can be produced, and is called an EPIR device.
What is needed is an EPIR device that requires less pulse voltage to switch the device, that exhibits greater resistance, that is protected from being damaged by a large pulse shock, and that has improved temperature properties and radiation hardness.